Abstract. A total of 340 cases of cutaneous neoplasia were diagnosed in 340 of 3,564 cats that were examined by biopsy or necropsy during a 41-month period from January I , 1986 through May 3 1, 1989. Eighteen types of tumor occurred, but four types comprised 77% of the cases. These were basal cell tum or, 89 cases (26%, mean age 10.3); mast cell tumor, 72 cases (21%, mean age 8.6); squamous cell carcinoma, 52 cases (15%, mean age 11.6); and fibrosarcoma, 50 cases (15%, mean age 10.2). For each of these four types of tumors , peak number of cases occurred in cats older than 10 years. Mast cell tum or was the only tumor diagnosed in cats younger than I year. The head was the most common site for basal cell tumors, mast cell tumors, and squamous cell carcinomas. The legs were the most common location of fi brosarcomas . Siamese cats had approximately three times as many mast cell tumors as statistically expected, but only one-fourth as many squamous cell carcinomas. Breed predilection for other skin tum ors was not apparent. Sex predilection was not detected for any skin tumor.Key words: Basal cell tumor; cat; cutaneous neoplasms; fibrosarcoma; mast cell tumor; squamous cell carcinoma. Resultssectioned, and stained with hemat oxylin and eosin, Other histologic stains (mainly, Giemsa and toluidine blue) were used at the discretion of the case pathologist.The histologic diagnosis, signalment, and sites of the tumors are summarized in Tables I , 2, and 3, Data were evaluated for statistical significance by adjusted chi-square analysis, Follow-up information was not available for these cats, Ski n tumors com prised 9. 6% of feline necr op sy or biopsy accessions during th e 41 -month study . The skin sites accounted for 29 .6% of all neoplasms diagnosed in the cats, m aking it the most common sit e for tumors in our laboratory, Eighteen different types ofcutane o us neoplasms were recognized . Sex di stribution and age ofaffected ca ts are su m marize d for each tumor in Table I. Sign ificant sex pred ilection wa s not apparent for an y skin tumor. Site d istribution of th e tumors is summarized in Table 3.Basal cell tumor, mast cell tumor, squamous cell carcinoma, and fibrosarcoma were the m ost commonly diagnosed tumors, com pris ing 77.1 % ofall skin tumors d iagnosed during th e study period. The in ciden ce of th ese four com m on tumors is su m marize d by breed in T able 2. Materials and MethodsIn most stud ies, skin has been second only to th e lymphoid syste m as the most co m m on site of tumors in th e caL I4.25.31.35 A lthough some ea rly surveys lack diagnoses of mast cell tumor,9,11 ,26 ba sal cell tumor,4.1 4.25.26 or fibrosarcoma," more recent British," German," and Swiss" reports have cited fibrosarcoma , basal cell tumor, squamous cell carcinoma, and mast cell tumor (with variation in order of prevalence) as th e most co m mon feline skin tumors. These fou r tumors had been reported as early as 1953 in a retrospec tive study of 26 feline skin tumors." Reports of breed,13,20,31 ,36 sex,23,31.34 and...

Abstract. The histologic and immunochemical characteristics of benign vascular tumors excised from the skin of seven young horses were evaluated. The patients were male horses of various breeds and were 16 months of age or younger at the time of presentation. Six tumors occurred on the extremities, and one was removed from the lip. Histologically, most tumors consisted of cellular nodules of varying compactness with few to many blood-filled lumina. Nodular growth separated preexisting adnexa and subcutaneous collagen. Some tumors contained or consisted predominantly of loosely packed arrays of ramifying arteries, veins, and capillaries separated by collagen within the dermis and subcutis. Within areas of nodular growth, multilayered vascular walls were encircled by reticulin strands that surrounded the endothelium and adjacent pericytes and also separated nonperivascular cells in the mass. Immunohistochemical staining of factor-VIII-related antigen and labeling by Ulex europeus-1 lectin was restricted to an innermost layer of cells surrounding vascular spaces, confirming their vascular endothelial origin. The plump fusiform cells arranged concentrically around the endothelium and some of those unassociated with vascular lumina stained with antibody to a-smooth muscle actin, as did the muscularis of larger vessels inside and outside of tumor nodules. These findings demonstrate an orderly arrangement between endothelium and supportive cells in these benign vascular neoplasms of young horses, similar to that observed during vascular development.

Abstract. Ten melanocytomas from 10 cattle were diagnosed by histopathologic examination of biopsy specimens submitted to the Veterinary Medical Diagnostic Laboratory, University of Missouri, between I January 1986 and 3 1 December 1993. One tumor was congenital; the others were first noticed between 2 months and 2 years of age (x = 9.9 months). Six tumors occurred in purebred (3) or crossbred (3) Angus cattle; one tumor each occurred in a Holstein, a Shorthorn, a Simmental, and a beef calf of unrecorded breed or coat color. Five calves were female, and five were male. Five tumors occurred in truncal dermis or subcutis (three in abdominal skin), four occurred on a limb, and one occurred on the jaw. Tumors varied in histologic appearance, but all were pigmented and all had few mitotic figures. Outcome was known for 8/10 cattle. In four cattle followed for at least 1 year, the tumor did not recur after surgical excision. Another heifer had residual gray tissue at the tumor site after surgery but remained in the herd without regrowth of the tumor 30 months after excision. Three other calves were slaughtered within 6 months of excision without apparent recurrence of the tumor.Key words: Cattle; congenital tumor; juvenile; melanocytic nevi; melanocytoma; neoplasia.Melanocytic tumors usually account for 5-6% of all tumors in surveys of bovine n e~p l a s m s~J~,~~,~* and occur most commonly in the s k h 6 J 4 A disproportionate number of reported cases have occurred in India,7,12,16,19,21,23,24,31,32,37 where predominantly gray cattle were affected.23 Black or red cattleI4 have been affected more commonly in Europe and North America. Although melanocytic tumors have been reported in older ~a t t l e ,~J~J~,~~ most cases have occurred in calves younger than 2 years.4,6J4J7Js,29,34,37,39 Neither site nor gender predilection has been apparent. In only a few reported cases has the tumor invaded deeper than the ~u b c u t i s~~~~~ or m e t a~t a s i z e d .~~,~~ The purpose of this retrospective study was to evaluate risk factors, pathologic features, and biologic behavior of bovine cutaneous melanocytic tumors. Materials and MethodsThe Veterinary Medical Diagnostic Laboratory files were searched retrospectively for all cases of melanocytic tumors in cattle from 1 January 1986 through 3 1 December 1993. Ten such tumors were encountered; all were biopsies of cutaneous masses submitted in 10% neutral buffered formalin for routine histologic processing. Paraffin-embedded sections were stained with hematoxylin and eosin. Serial sections of each tumor were also treated with 0.25% potassium permanganate and washed in 5% oxalic acid to bleach melanin before staining with hematoxylin and eosin. Tumors were classified30 as junctional or dermal when possible.

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